import sys
sys.setrecursionlimit(10**6)

n = int(input())
graph = [[] for _ in range(n)]

for i in range(n-1):
    u, v, w = map(int, input().split())
    graph[u-1].append((v-1, w))
    graph[v-1].append((u-1, w))

ans = 0

def dfs(v, p):
    global ans
    dists = []
    for u, w in graph[v]:
        if u == p:
            continue
        dists.append(dfs(u, v) + w)
    dists.sort(reverse=True)
    if len(dists) >= 1:
        ans = max(ans, dists[0])
    if len(dists) >= 2:
        ans = max(ans, dists[0] + dists[1])
    return max(0, dists[0]) if dists else 0

dfs(0, -1)
print(ans)